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[209.85.128.175]) by smtp.gmail.com with ESMTPSA id v67-20020a379346000000b0069bdb3bb132sm7681292qkd.37.2022.04.26.21.31.23 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Apr 2022 21:31:24 -0700 (PDT) Received: by mail-yw1-f175.google.com with SMTP id 00721157ae682-2f7c57ee6feso5923327b3.2 for ; Tue, 26 Apr 2022 21:31:23 -0700 (PDT) X-Received: by 2002:a0d:cb41:0:b0:2f7:d205:9c99 with SMTP id n62-20020a0dcb41000000b002f7d2059c99mr17141871ywd.417.1651033882822; Tue, 26 Apr 2022 21:31:22 -0700 (PDT) MIME-Version: 1.0 References: <20220426125751.108293-1-nicolas.dufresne@collabora.com> <20220426125751.108293-4-nicolas.dufresne@collabora.com> In-Reply-To: <20220426125751.108293-4-nicolas.dufresne@collabora.com> From: Tomasz Figa Date: Wed, 27 Apr 2022 13:31:11 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v4 03/24] media: videobuf2-v4l2: Warn on holding buffers without support To: Nicolas Dufresne , Marek Szyprowski , Mauro Carvalho Chehab , Hans Verkuil Cc: nicolas@ndufresne.ca, Sebastian Fricke , linux-media@vger.kernel.org, Ezequiel Garcia , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-2.5 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RDNS_NONE,SPF_HELO_NONE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Nicolas, Sebastian, On Tue, Apr 26, 2022 at 9:58 PM Nicolas Dufresne wrote: > > From: Sebastian Fricke > > Using V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF flag without specifying the > subsystem flag VB2_V4L2_FL_SUPPORTS_M2M_HOLD_CAPTURE_BUF, results in > silently ignoring it. > Warn the user via a debug print when the flag is requested but ignored > by the videobuf2 framework. > > Signed-off-by: Sebastian Fricke > Signed-off-by: Nicolas Dufresne > Reviewed-by: Ezequiel Garcia > --- > drivers/media/common/videobuf2/videobuf2-v4l2.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > Thanks for the patch. Please see my comments inline. > diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c > index 6edf4508c636..812c8d1962e0 100644 > --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c > +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c > @@ -329,8 +329,13 @@ static int vb2_fill_vb2_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b > */ > vbuf->flags &= ~V4L2_BUF_FLAG_TIMECODE; > vbuf->field = b->field; > - if (!(q->subsystem_flags & VB2_V4L2_FL_SUPPORTS_M2M_HOLD_CAPTURE_BUF)) > + if (!(q->subsystem_flags & VB2_V4L2_FL_SUPPORTS_M2M_HOLD_CAPTURE_BUF)) { > + if (vbuf->flags & V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF) > + dprintk(q, 1, > + "Request holding buffer (%d), unsupported on output queue\n", > + b->index); I wonder if we shouldn't just fail such a QBUF operation. Otherwise the application would get unexpected behavior from the kernel. Although it might be too late to do it now if there are applications that rely on this implicit ignore... Best regards, Tomasz